Form supporting girder for use in concrete construction



P 1962 H. A. DE LA RAMBELJE 3,054,486

FORM SUPPORTING GIRDER FOR USE IN CONCRETE CONSTRUCTION Filed June 29,1961 2 Sheets-Sheet 1 L" I I INVENTOR.

HENRY A. DE LA RAMBELJE Sept. 18, 1962 H. A. DE LA RAMBELJE FORMSUPPORTING GIRDER FOR USE IN CONCRETE CONSTRUCTION Filed June 29, 1961 2Sheets-Sheet 2 HHEEQED INV EN TOR.

HENRY A. DE LA RAMBELJE Z BY 2 ATTORNEYS."

United rates 3,h54,486 Patented Sept. 18, 1962 flice 3,954,486 FQRNISUPPORTING GIRDER FOR USE ns CONCRETE CSNSTRUCTION Henry A. de laRambelje, Richmond Hill, N.Y., assignor to Hico Corporation of America,New York, N.Y., a

corporation of N ew York Filed June 29, 1961, Ser. No. 120,733 12(films. (Cl. 189-37) The invention relates to adjustable form supportinggirders for concrete construction, and more particularly to improvementsin girders of the telescopic type.

In my copending application, Serial No. 17,117, filed March 23, 1960, Ihave explained some of the difliculties which have been encountered inattempting to adapt telescopic girder design to the production ofgirders made of a light metal, more especially aluminum. In thatapplication, I disclosed a solution to the problem of how to avoid, orminimize, the effects of the phenomenon known as flare-out. Otherproblems have had to be met, including the fundamental one created bythe fact that structural aluminum alloys have a modulus of elasticitywhich is only about one third that of structural steel. Contemplation ofthis fact suggests that the use of aluminum would seem to impose theneed for beams of greater depth and section thickness, with somesacrifice in compactness and weight saving. However, I have discovered aunique combination of structural features which make it possible toobtain, in an aluminum girder of very closely the same depth as acomparable steel girder, deflection values approximately equal to thoseof the steel girder. Contributing to this accomplishment is theprovision of an improved girder section of box form constructed of twoextruded channel sections, one carnbered and the other straight, the twowelded together in a fashion which preserves the camber of the onesection while producing a greater depth of the box section where thebending moment is greatest, and while at the same time reinforcing thesides of the section against buckling. Further contributing to suchaccomplishment is the provision of a unique form of extruded l beamsection having thickened, upwardly canted and edge reinforced, upperflanges, and having a web portion of increased thickness at its upperend to resist torsion applied through the flanges at the axis ofintersections of the web and flanges. These and other features andadvantages of my invention will now be described more fully withreference to the drawings illustrative of the best mode contemplated byme for carrying out my invention.

FIG. 1 is a side elevational view, partly in vertical section, of agirder constructed in accordance with my invention, showing the girderin place and ready for use. The initial camber of the girder has beensomewhat exaggerated to show it more clearly.

FIG. 2 is a similar View, showing the girder deflected under the weightof the poured concrete.

FIG. 3 is a detail perspective view of the meeting ends of two girders,and shows the supporting brackets for both the I-beam and box sectionsof the girder.

FIG. 4 is an enlarged vertical transverse sectional View taken asindicated at 44 in FIG. 1.

FIG. 5 is a similar sectional view taken at 55 of FIG. 1.

My adjustable form supporting girder comprises, in its generalarrangement, a cambered box-like section 1. and an I-beam section 2slidable lengthwise within the box-like section for adjustment of thelength of the girder, and locking means 3 for holding an outer endsurface of the I-beam section pressed against an inner surface of thebox-like section. The cambered box-like section is constructed of twochannel-shaped members 4 and 5 arranged in opposed relationship withportions of the flanges 6, 6 of one of such members overlapping portionsof the flanges 7, 7 of the other. Member 4 is cambered lengthwise of thegirder as can be discerned in FIG. 1, and as will be further understoodfrom a comparison of FIGS. 4 and 5, noting that at the FIG. 5 sectionthe top of the girder is higher than it is at the FIG. 4 section. Also,the lower edges 8 of flanges 6 assume the same arc of camber as does thetop sur face of member 4. However, member 5 is not cambered at all, butis perfectly straight from end to end.

My concept of making the box section of the girder from two channelsections, one cambered and the other straight, produces a number ofhighly advantageous new results: (1) the two channel sections arefavorably designed for fabrication by the aluminum extrusion process;(2) cambering is simplified by reason of the fact that it is quite easyto camber the upper channel with the use of standard rolling equipment,whereas to camber a box section requires more elaborate specialmachinery, and also because the lower half of the box section need notbe subjected to cambering work; (3) the resulting box section is deeperwhere the bending moment is greatestcompare FIGS. 4 and 5 and therelative location of the 44 and 55 section lines in FIG. 1; (4) theoverlapping flanges or the cambered and straight channels stiffen thesides of the box section against buckling; (5) because the upper edgesof flanges 7 of the lower channel are perfectly straight, no specialwelding procedure or equipment is required to weld the two channelstogether, for, notwithstanding the camber of the upper channel 4, astraight line of welding is provided at 9, with the result that the seamwelds run parallel with the straight bottom chord, permitting the use ofconventional automatic welding equipment; and (6) by reason of thegreater depth of the cross-section of the box toward the central portionof the girder, an increased vertical clearance is obtained between thetwo girder sections toward such central portion, with the result ofallowing a greater degree of angling of the one section relative to theother for easier assembly and easier stripping of the girder from theconstruction after setting of the concrete.

In my preferred girder construction, the overlapping portions of theflanges of the two channel members which form the box section are oflsetlaterally of the girder to permit the main bodies of the flanges 6, 6and 7, 7 to be coplanar. In the particular construction shown, flanges7, 7 of the lower channel are offset outwardly, as at 10, 10, and haveshoulders 11, 11 which serve as and bearings for the ends 8, 8 offlanges 6, 6 of the upper channel when the two channels are assembledfor welding. The oflset portions 1t), 10 of flanges 7, 7 are ofsuflicient depth to maintain the overlap of the two channels at thedeepest cross-section of the box.

I-beam section 2 of the girder preferably is cambered lengthwise toaccommodate it to the camber of the boxlike section. Such camberedI-beam section is of uniform depth throughout its length so that thegreater depth of the cross-section of the box toward the central portionof the assembled girder will aflord increased vertical clearance betweenthe two girder sections toward such central portion, yielding theadvantage heretofore described relative to easier stripping of thegirder from the forms after setting of the concrete.

The bending moment of the I-beam section is increased and madecompatible with the bending moment of the strengthened camberconstruction of the box section by canting the upper flanges 12 of theI-beam upwardly and outwardly, FIG. 4, making such flanges of increasedthickness relative to the lower flanges thereof, and forming them withthickened outer edges 13. Also contributing to the increased bendingmoment is the increased thickness of the upper portion 14 of the web ofthe I relative to the main body 15 of the web. The thickness and taperof web portion 14 have further been found to be of considerablepractical value in resisting torsion applied through the canted flanges12 at the axis of intersectio of the planes of such flanges and web 15.I

Further contributing to the bending strength and low deflection value ofthe special I-beam and cambered box sections of my improved girder, isthe significant design principle of the locking means which holds thetwo sections in their proper relation of predetermined camber in any ofseveral positions of length adjustment. A most effective transmissionand distribution of stresses between the I and box sections is securedthrough the use of an externally threaded tube 16 of a diameter which islarge enough to directly engage a substantial area of both lower flangesof the I beam. This threaded tube engages a nut plate 17 bearing againstthe inner bottom of the box section. Threaded tube 16 has a collar 18 atits upper end, providing a limit stop against the nut plate, the tubeand nut plate comprising a sub-assembly which is put together with thebox section by insertion through the open end thereof and locked inplace after assembly of the two sections of the girder by tightening thethreaded tube against the outer surface of the lower flanges of theI-beam section. Tightening is easily performed by means of a wrench orsuitable bar inserted in opening 19 of the tube. The tube and nut plateare desirably made of galvanized steel.

The girder sections are provided with suitable end supporting brackets20, 21, FIG. 3, whose flanges 22, 23 will rest on top of beams orledgers 24 in accustomed fashion. Normally the girders are placed tosupport plywood or other suitable forms 25 to carry the poured concreteC. A comparison of FIGS. 1 and 2 will show how the camber of the freegirder (FIG. 1, camber exaggerated) subsides under the load imposed bythe concrete (FIG. 2). Notice that upper channel section 4 is cambered,lower channel section straight in FIG. 1, whereas this condition isexactly reversed in FIG. 2 where the upper channel has straightened out,imposing a downward curvature upon the lower channel. Notice also line8, curved in FIG. 1, straight in FIG. 2; and line 11, straight in FIG;1, curved in FIG. 2.

While my improved girder and girder sections have been developedprimarily to meet the special problems encountered in the production ofgirders made of aluminum alloys possessing a modulus of elasticity muchlower than that of steel, I recognize that some or all of the structuralfeatures I have disclosed can beof value for use in girders of othermaterials, not excepting steel, and including, for example, fiberglassor other structural plastic resin products.

The terms and expressions which I have employed are used in adescriptive and not a limiting sense, and I have no intention ofexcluding equivalents of the invention described and claimed.

I claim:

1. An adjustable cambered form-supporting girder for concreteconstruction comprising a cambered box-like section and an I-beamsection slidable lengthwise within the cambered box-like section foradjustment of the length of the girder, locking means for holding anouter end surface of the I-beam section pressed against an inner surfaceof the cambered box-like section, said cambered box-like section beingconstructed of two channel-shaped members arranged in opposedrelationship with portions of the flanges of one of the channel-shapedmembers overlapping portions of the flanges of the other, the onechannel-shaped member being cambered lengthwise and the other beingstraight, and the overlapping portions of the flanges of the two beingsecured together to provide a box-like section having a cambered uppersurface and a straight lower surface, the cross-section of the box beingof greater depth toward the central portion of the assembled girder thanat the free end of the box-like section.

2. An adjustable cambered form-supporting girder according to claim 1,in which the overlappingportions of the flanges of said otherchannel-shaped member are offset laterally of the girder to permit themain bodies of said flanges to be coplanar with the flanges of thefirstnamed channel-shaped member, such offset portions being ofsuflicient depth to maintain the overlap of the two channel-shapedmembers at the deepest cross-section of the box.

3. An adjustable cambered form-supporting girder according to claim 1,in which said I beam section is cambered lengthwise to accommodate it tothe camber of the box-like section, the I-beam section being of uniformdepth throughout its length whereby the greater depth of thecross-section of the box toward the central portion of the assembledgirder aflords increased vertical clearance between the two girdersections toward such central portion, thus to allow a greater degree ofangling of the one section relative to the other for easier stripping ofthe girder from the construction after setting of the concrete.

4. An adjustable cambered form-supporting girder according to claim 1,in which the bending moment of the I-beam section is made compatiblewith the bending moment of the strengthened camber construction of theboxlike section by canting the upper flanges of the I-beam upwardly andoutwardly.

5. An adjustable cambered form-supporting girder according to claim 1,in which the bending moment of the I-beam section is made compatiblewith the bending moment of the strengthened camber construction of theboxlike section by making the upper flanges of the I-beam of increasedthickness relative to the lower flanges thereof.

6. An adjustable cambered form-supporting girder according to claim 1,in which the bending moment of the I -beam section is made compatiblewith the bending moment of the strengthened camber construction of thebox-like section by canting the upper flanges of the I-beam upwardly andoutwardly and making such flanges of increased thickness relative to thelower flanges of the I- beam.

7. An adjustable cambered form-supporting girder according to claim 1,in which the overlapping flanges of the cambered and straightchannel-shaped members of the box-like section of the girder are securedtogether by a straight line weld following the straight edges of theflanges of the straight member at a progressively varying distance fromthe curved edges of the flanges of the cambered member 8. A box-likesection for an adjustable cambered formsupporting girder for concreteconstruction, said boxlike section being constructed of twochannel-shaped members arranged in opposed relationship with portions ofthe flanges of one of the channel-shaped members overlapping portions ofthe flanges of the other, the one channel-shaped member being camberedlengthwise and the other being straight, and the overlapping portions ofthe flanges of the two-being secured together to provide a box-likesection having a cambered upper surface and a straight lower surface,the cross-section of the box being of greater depth toward the centralportion of the girder than at the free end of the box-like section.

9. A box-like section for an adjustable cambered formsupporting girderaccording to claim 8, in which the overlapping portions of the flangesof said other channelshaped member are offset laterally of the girder topermit the main bodies of said flanges to be coplanar with the flangesof the first-named channel-shaped member, such offset portions being ofsufficient depth to maintain the overlap of the two channel-shapedmembers at the deepest cross-section of the box.

10. A box-like section for an adjustable cambered formsupporting girderaccording to claim 8, in which the overlapping flanges of the camberedand straight channelshaped members are secured together by a straightline Weld following the straight edges of the flanges of the straightmember at a progressively varying distance from the curved edges of theflanges of the cambered member.

11. An adjustable cambered form-supporting girder according to claim 1,in which said locking means comprises an externally threaded tubeengaging a nut plate bearing against the inner bottom of the box-likesection of the girder, said threaded tube directly engaging asubstantial area of both lower flanges of the I-beam section of thegirder.

12. An adjustable cambered form-supporting girder according to claim 1,in which said locking means cornprises an externally threaded tubeengaging a nut plate bearing against the inner bottom of the box-likesection of the girder, said threaded tube directly engaging asubstantial area of both lower flanges of the I-beam section of thegirder and having a collar at its upper end providing a limit stopagainst the nut plate, the tube and nut plate comprising a sub-assemblywhich is assembled with said box-like section by insertion through theopen end thereof and locked in place after assembly of the two sectionsof the girder by tightening the threaded tube against the outer surfaceof the lower flanges of the I- beam section.

References Cited in the file of this patent UNITED STATES PATENTS758,529 Grey Apr. 26, 1904 2,386,161 Hawes Oct. 2, 1945 2,737,117Randall Feb. 7, 1956 FOREIGN PATENTS 21,895/11 Great Britain Oct. 3,1912 429,325 Great Britain May 28, 1935 337,322 Switzerland May 15, 19591,218,573 France Dec. 21, 1959 :UNITED STATES PATENT OFFICE CERTIFIQATE0F CORECTION Patent No, 3,054,486 September 18, 1962 Henry Ao de laRambelje It is hereby certified that error appears in the above numberedpatent requiring correction and that the said Letters Patent shouldvread as corrected below.

Columh 4, line 55, for "twobeing" read two being column 6, line 11, for"2,737,117" read 2,734,117

Signed and sealed this 5th day of March 1963.

(SEAL) Attest:

ESTON G, JOHNSON DAVID LLADD Attesting Officer Commissioner of Patents

